The wireless cellular network provides mobile users with communication services such as voice, data and etc by utilizing a network structure of cells. Normally, a cell provides a wireless transmission coverage in a certain area. Wherein, a Macrocell is of a largest wireless transmission radius, and multiple Macrocells may realize seamless wireless transmission coverage in a large area. A base station supporting the Macrocell is called a Macrocell base station, the transmission power of which is relatively high and the antenna of which is established at a relatively high place, e.g., the base station in a 3GPP network, namely Node B, or the base station in a 3GPP LTE (3GPP Long Term Evolution) network, namely eNode B (eNB), or etc.
In order to enlarge the capacity of the wireless cellular network and improve the quality of the wireless communication services in the coverage area of the wireless cellular network, wireless cells which have a wireless transmission radius smaller than that of the Macrocell may be adopted in hotspot areas and in doors, e.g., Microcells, Picocells, Femtocells and etc. Normally, compared with the base station supporting the Macrocell, the base stations that support these wireless cells having a wireless transmission radius smaller than the Macrocell's have a lower transmission power, and their antennas are established at a lower place.
Usually, the aforementioned wireless cells having different transmission radii may exist in some areas simultaneously, and in this case, the base stations of the wireless cells having different transmission radii provide overlapping coverage of at least two wireless networks within the overlapped coverage areas of these base stations. That is to say, the wireless cell having a larger transmission radius, e.g., the Macrocell, provides coverage of one wireless network, and the wireless cell having a smaller transmission radius, e.g., the Microcell, provides coverage of another wireless network.
In an area with coverage of at least two wireless networks, a User Equipment (UE) of a mobile user may select to access a large-cell network or a small-cell network. For example, in the 3GPP network, a Node B supports Macrocell coverage while an HNB supports Femtocell coverage, and a UE may select to access the Node B or the HNB in the overlapping area with coverage of the Node B and the HNB. For another example, in the 3GPP LTE network, an eNB supports Macrocell coverage while an HeNB supports Femtocell coverage, and the UE may select to access the eNB or the HeNB in the overlapped area with coverage of the eNB's and the HeNB. In the present invention, for convenience of description, the UE accessing the large-cell base station is called a large-cell UE while the one accessing the small-cell base station is called a Home UE (HUE).
In the aforementioned communication environment with coverage of at least two wireless networks, the two wireless networks may adopt a same spectrum or different spectrums. For example, if an available spectrum bandwidth for the two wireless networks is 20 MHz, both the large-cell network and the small-cell network can use this spectrum resource of 20 MHz when the two wireless networks adopt the same spectrum, or the available spectrum bandwidth can be divided into several parts which can be allocated to the two wireless networks when the two wireless networks adopt different spectrums, i.e., the large-cell network can use a part of the spectrum resource, e.g., 15 MHz, and the small-cell network can use the left part of the spectrum resource, e.g., 5 MHz.
There exists a co-channel interference between the two wireless networks when the large-cell network and the small-cell network adopts the same spectrum, or there exists a different-channel interference between the two wireless networks when the large-cell network and the small-cell network adopts different spectrums, or there exists an adjacent-channel interference between the two wireless networks when the large-cell network and the small-cell network adopts adjacent different spectrums. And usually, the shared-channel interference is much higher than the adjacent-channel interference or other different-channel interference. And thus, there are four kinds of uplink and downlink interference between the two wireless networks in a Frequency Division Duplex (FDD) system, including: the downlink interference from the large-cell base station to the HUE, the downlink interference from the small-cell base station to the large-cell UE, the uplink interference from the HUE to the large-cell base station and the uplink interference from the large-cell UE to the small-cell base station. By sharing the same spectrum between the two wireless networks, each wireless network can have more available spectrum resources, however, it will make greater shared-channel interference arose between the two wireless networks, which, in contrast, will decrease network capacity of the wireless networks. On the other hand, there exists a less different-channel interference between the two wireless networks when different spectrums are adopted therein while it makes each wireless network have less available spectrum resources. It can be seen based on the analysis that both higher interference and less available spectrum resources will decrease the network capacity of the wireless network and utilization efficiency of the spectrum in an environment with coverage of two wireless networks is thus relatively low.